title: Batch anaerobic co-digestion of cow manure and waste milk in two-stage process for hydrogen and methane productions.
abstract: Anaerobic co-digestion of cow manure (CM) and waste milk (WM), produced by sick cows during treatment with antibiotics, was evaluated in two-stage process under thermophilic condition (55 °C) to determine the effect of WM addition on hydrogen (H2) and methane (CH4) production potentials, volatile solids (VS) removal, and energy recovery. Six CM to WM VS ratios of 100:0, 90:10, 70:30, 50:50, 30:70, and 10:90 were examined using 1-L batch digesters. The WM VS ratio of 30 % was found to be the minimum limit for significant increases in specific H2 and CH4 yields, and VS removal as compared to digestion of manure alone (P < 0.05). The highest specific H2 and CH4 yields, VS removal and energy yield were 38.2 mL/g VS, 627.6 mL/g VS, 78.4 % and 25,459.8 kJ/kg VS, respectively, in CM:WM 30:70. Lag phases to H2 and CH4 productions were observed in CM-WM mixtures, increased with increasing the amount of WM in the feedstock and were greater than 72 h in CM:WM 50:50 and 30:70. The digestion system failed in CM:WM 10:90. The results suggest that CM:WM 30:70 was optimum, however, due to limited amount of WM usually generated and long lag phase at this ratio which may make the process uneconomical, CM:WM 70:30 is recommended in practice.
authors.affiliation: Graduate School of Animal and Food Hygiene, Obihiro University of Agriculture and Veterinary Medicine, Obihiro, Hokkaido, 080-8555, Japan.
authors.forename: Suraju A
authors.initials: SA
authors.lastname: Lateef
authors.forename: Nilmini
authors.initials: N
authors.lastname: Beneragama
authors.forename: Takaki
authors.initials: T
authors.lastname: Yamashiro
authors.forename: Masahiro
authors.initials: M
authors.lastname: Iwasaki
authors.forename: Kazutaka
authors.initials: K
authors.lastname: Umetsu
mesh_terms: D000693:Anaerobiosis; D000818:Animals; D056804:Biofuels; D002417:Cattle; D006859:Hydrogen / Q000378:metabolism*; D007220:Industrial Waste; D008372:Manure; D008697:Methane / Q000096:biosynthesis*; D008892:Milk
chemical_list: D056804:Biofuels; D007220:Industrial Waste; D008372:Manure; D006859:Hydrogen; D008697:Methane